Method and apparatus for cleaning surfaces

ABSTRACT

A surface cleaning device for cleaning a surface of a solar panel, wherein the surface cleaning device may include: a first dust carrying member; a second dust carrying member; a motor; and a motion delay assembly. The first dust carrying member and the second dust carrying member are coupled to the motor; wherein the motor is configured to cyclically move the first dust carrying member and the second dust carrying member along a path. The motion delay assembly is configured to cyclically introduce a momentarily delay in a progress of the first dust carrying member along the path, while the second dust carrying member contacts the surface thereby reducing a gap between the first dust carrying member and the second dust carrying member and induce air to exit the gap and progress along the surface and remove dust that precedes the second dust carrying member.

CROSS REFERENCE

This application is a continuation in part of PCT patent applicationPCT/IL2017/050762 international filing date Jul. 7, 2017 that claimspriority from U.S. provisional patent 62/359,955 filing date Jul. 8,2017.

This application claims priority from U.S. provisional patent 62/627,781filing date Feb. 8, 2018.

FIELD OF THE INVENTION

The present disclosure relates to the field of surface cleaning devices.

BACKGROUND OF THE INVENTION

Dust can be collected on surfaces of different kinds and can adverselyaffect operation of devices associated with the dust covered surfaces.One example of a surface that can be negatively affected by dustcollection is a surface of a photovoltaic (“PV”) panel (also referred toas a solar panel).

PV panels are most efficiently utilized in sunny areas.

Manny sunny areas globally suffer mostly from dust. Dust that iscollected on the (usually glass), surface of PV panels can reduce theirradiation that hit the silicon layer (of the PV panel) by up to 20%.

Most sunny places are located between the Tropic of Cancer and theTropic of Capricorn where trackers and roof top net-meteringconfigurations are mostly popular.

In a photovoltaic (PV) array, a plurality of solar panels are mounttogether adjacent to each and may be mounted on big and long tables.

Single Axes PV trackers and roof top tables are usually small in widthand length. For example, a fixed tilt solar table is usually includesbetween 4-7 row of solar panels by 100-150 panels in series (total of400-1000 panels per table) while in trackers and in roof topsinstallations the table can be as small as 1 row by 40 panels (40 panelper table).

Still those small tables suffer a lot from dust coverage, which impactthe effective radiation (photon) reaching the panel.

Areas (such as deserts) with high irradiation usually suffer from dustand their solar panels usually require more frequent cleaning procedureswhich manually are very costly.

Robotic cleaning devices must be used. Nevertheless—using a single robotper a solar panel that includes only 40 panels table (each table)instead of 1000 panels table the economics of the cost benefit isdifferent and can kill the investor interests.

Another factor that influences the PV eco-system is that the system costdecreases as a result of the tariff reduction for KWh (from around0.4/KWh in 2009 to less than 0.07/KWh in 2016).

This new eco-system favors cleaning devices which can operateautonomously.

Preferably a cleaning system should consume fewer materials and consumeless energy while still effectively cleaning.

Some examples of the cleaning device according to the present disclosurecan support dry, waterless environment friendly operation, which can bebeneficial in desert and dry areas with lack of portable water.

Dust can cause a reduction of up to 20% in yield. PV fields in desertclimate also suffer from lack of water and access to water pipe.

There is thus a need for frequent cleaning that makes sense in the newworld where the value gain from the cleaning is lower (due to tariff)and the size of the table can be in an order of magnitude smaller.

Some places suffer from dew during night or evening time in one or 2seasons a year. Cleaning with a dry method, when dew occurs, turns thedust into mud and eliminates the ability to use dry apparatus forcleaning.

In such case a fast cleaning must be supported so that cleaning can becompleted during afternoon in a fast way.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter regarded as the invention is particularly pointed outand distinctly claimed in the concluding portion of the specification.The invention, however, both as to organization and method of operation,together with objects, features, and advantages thereof, may best beunderstood by reference to the following detailed description when readwith the accompanying drawings in which:

FIG. 1 illustrates an example of a surface cleaner when moving from aright side of a surface to a left side of the surface in diagonalcrisscross way;

FIG. 2 illustrates an example of a surface cleaner when the cleaningdevice hits an end of table stopper positioned at the end of the table;

FIG. 3 illustrates an example of a surface cleaner at an end of aturning movement, which change the diagonal direction, this is also thestarting position of the surface cleaner while moving toward the rightside;

FIG. 4 illustrates an example of a surface cleaner when the surfacecleaner is normal to a longitudinal axis of the surface;

FIG. 5 illustrates an example of a surface cleaner at two differentpoints of time;

FIGS. 6A-6B, 2C and 2D illustrate an example of a surface cleaner at twodifferent points of time during a same cleaning cycle;

FIG. 7 illustrates an example of a surface cleaner that is moved betweensurfaces by a drone;

FIG. 8 illustrates an example of a surface cleaner that is moved betweensurfaces by a robotic arm;

FIG. 9 illustrates an example of a surface cleaning device;

FIG. 10 illustrates an example of a surface cleaning device;

FIG. 11 illustrates an example of a surface cleaning device;

FIG. 12 illustrates an examples of interfacing elements;

FIG. 13 illustrates an example of a surface cleaning device;

FIG. 14 illustrates an example of a surface cleaning device;

FIG. 15 illustrates an example of a surface cleaning device;

FIG. 16 illustrates an example of a surface cleaning device;

FIG. 17 illustrates an example of a surface cleaning device;

FIG. 18 illustrates an example of a surface cleaning device;

FIG. 19 illustrates an example of at least a portion of a surfacecleaning device;

FIG. 20 illustrates an example of at least a portion of a surfacecleaning device;

FIG. 21 illustrates an example of a table and of at least a portion of asurface cleaning device;

FIG. 22 illustrates an example of a method;

FIG. 23 illustrates an example of at least a portion of a surfacecleaning device;

FIG. 24 illustrates an example of at least a portion of a surfacecleaning device;

FIG. 25 illustrates an example of at least a portion of a surfacecleaning device;

FIG. 26 illustrates an example of at least a portion of a surfacecleaning device;

FIG. 27 illustrates an example of at least a portion of a surfacecleaning device; and

FIG. 28 illustrates an example of at least a portion of a surfacecleaning device.

FIG. 29 illustrates an example of at least a portion of a surfacecleaning device;

FIG. 30 illustrates an example of at least a portion of a surfacecleaning device; and

FIG. 31 illustrates an example of at least a portion of a surfacecleaning device.

DETAILED DESCRIPTION OF THE DRAWINGS

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those skilled in the art that thepresent invention may be practiced without these specific details. Inother instances, well-known methods, procedures, and components have notbeen described in detail so as not to obscure the present invention.

The subject matter regarded as the invention is particularly pointed outand distinctly claimed in the concluding portion of the specification.The invention, however, both as to organization and method of operation,together with objects, features, and advantages thereof, may best beunderstood by reference to the following detailed description when readwith the accompanying drawings.

It will be appreciated that for simplicity and clarity of illustration,elements shown in the figures have not necessarily been drawn to scale.For example, the dimensions of some of the elements may be exaggeratedrelative to other elements for clarity. Further, where consideredappropriate, reference numerals may be repeated among the figures toindicate corresponding or analogous elements.

Because the illustrated embodiments of the present invention may for themost part, be implemented using electronic components and circuits knownto those skilled in the art, details will not be explained in anygreater extent than that considered necessary as illustrated above, forthe understanding and appreciation of the underlying concepts of thepresent invention and in order not to obfuscate or distract from theteachings of the present invention.

Any reference in the specification to a method should be applied mutatismutandis to a system or device, unit, mechanism, circuit or apparatuscapable of executing the method.

Any reference in the specification to a system, device, unit, mechanism,circuit or apparatus, should be applied mutatis mutandis to a methodthat may be executed by the system, device, unit, mechanism, circuit orapparatus.

The terms system, device, unit, mechanism, circuit, and apparatus areused in an interchangeable manner.

The terms rod, pipe and axis are used in an interchangeable manner.

Two directions are generally the same (or belong to the same generaldirection) when they are equal to each other or do not deviate from eachother by more than ninety degrees.

The term “substantially”—unless stated otherwise may refer to adeviation of few percent (for example—deviation of less than 10% or lessthan 20 percent).

The terms “cleaning elements”, wipers and “dust carrying members” areused in an interchangeable manner. A dust carrying member is a physicalelement that is capable of moving dust when contacting the dust duringmovement (and/or when static). The dust carrying member may absorb oraggregate dust or may not aggregate or absorb dust.

Any combination of any system, device, unit, mechanism, circuit, moduleor component listed in any of the figures, any part of the specificationand/or any claims may be provided. Especially any combination of anyclaimed feature may be provided.

Any of the surface cleaning device referred to in the specificationand/or drawings may perform dry cleaning—without using any fluid toclean the dust or substantially without using fluid to clean the dust.Substantially in this sense means that most of the cleaning process (forexample—more than 80% or 90%) is performs by dry cleaning techniques.

The surface cleaning device can employ a single pipe of rotating wiperswhich may be moved in relation to the surface by a movement mechanismthat may include two wagons that drive along the table with or withoutspecial rails (Optional—driving directly on the panels).

The surface cleaning device can simplify the process of dry cleaningapparatus to the minimum component, which allows the surface cleaningdevice to fit the new eco-system of low income and low benefit generatedfrom a clean panels and smaller size of panels' table on roof tops andon single axes tracker.

The surface cleaning device 100 of FIG. 1 may include: (a) a movementmechanism that may include upper wagon 3, lower wagon 9 that have withwheels, (b) a pivot pole 5 (also referred to as axis of rotation) thatmay be mechanically coupled to the wheels by bearing 2, (c) an engine 13for moving the lower wagon, (d) a motor 1 for moving the wipers—forexample by rotating the pivot pipe, (d) four wipers 4 (may be four rowsof wipers) that are mechanically coupled to pivot pipe 5, (e) battery14, and (f) left shaker pipe 6 and right shaker pipe 6′ that arepositioned on different sides of the pivot pole 5.

The surface cleaning device 100 is lightweight—and represents areduction of weight in one order of magnitude from tens of kg (25-90 kg)to less than 5-8 kg. These weights is merely a non-limiting example ofthe weight of the surface cleaning device. Decreasing the weight of thesurface cleaning device allow to reduce the cost of components (such assteel) of the surface cleaning device and allows to reduce anysupporting mechanism (such as rails 11) and consume less energy—thusrequired a lighter energy source.

Optionally, the energy unit for operation of the surface cleaning devicecan be based on charging a battery through the day by solar panel andactivating the engines on energy provided by the battery when cleaningprocedure is required.

The low weight surface cleaning device may be easily carried from onetable to the other by drone or light robotic arm (see FIGS. 7 and 8).

The surface cleaning device may move while being at any angle inrelation to the longitudinal axis of the panel. The angle may changeover time, may remain the same, may change depending on the tilt angle(in relation to the horizon) of the panel, may change in relation to thedirection of movement of the surface cleaning device, may change basedon environmental conditions, and the like.

FIGS. 1-3 illustrates the surface cleaning device 100 as moving in atilted angle (that is not normal to the longitudinal axis of the panel)when progressing towards the left end of the panel and then moving atanother tilted angle when progressing towards the right end of thepanel.

The movement is referred to as a crisscross diagonal crisscrossmovement.

In FIGS. 1-3 the upper end of the surface cleaning device precedes thelower end of the surface cleaning device—thereby allowing removed dustto be moved away from the panel. When tilted at such tilt angle dustshould not fall back on the surface cleaning device.

Accordingly—the dust removal may benefit from the dust removaloperations executed by the surface cleaning device and also benefit fromgravity.

In FIG. 1 the surface cleaning device moves toward the left end of thepanel (arrow 12 represents this movement) and at least most of the dustthat is removed by the surface cleaning device is directed in a generaldirection that is normal to the tilt angle—and does not come backtowards the surface cleaning device.

Assuming that the table is tilted (within a plane that is normal to theplane of FIG. 1) the surface cleaning device removes dust that will falldownwards and not be carried by the surface cleaning device during theentire progress from one end of the table to another end of the table.

Optionally the tilt angle may range between 20-40 degrees from alatitudinal axis of the table. For example, when the tile angle isthirty degrees in relation to the latitudinal axis of the table and thewidth of the table is 2 meters—dust particles will be carried over lessthan 2.5 meters (in average). If considering that the tilt of the tableis above zero than the wind blowing and gravitation will carry the dustparticle along a much shorter way. Other parameters and configurationscan be used.

Optionally, the surface cleaning device can improve the air blowingeffect, which can help to reduce the scratches impact and reduce theamount of time the surface cleaning device needs to travel for reachingninety nine percent efficiency of dust removal, due to spraying the dustbackward (pick the dust up by the microfiber and sending it backward dueto the centrifuge power and hitting the panels surface again with dustparticles).

The diagonal movement of the surface cleaning device may be optimizedwhen the motorized mechanism includes only one engine and is configuredto push the surface cleaning device for progressing from one end of thepanel to another.

Referring to FIGS. 1 and 2—the upper rail 11 and the lower rail 11′extend beyond the left end of the table and beyond the right end of thetable.

There is a left pivot 10 that precedes the left end of the table and aright pivot 10 that precedes the right end of the table.

The upper rail 11 may include three segments—left segment, intermediatesegment and right segment. These segments are virtually partitioned byleft pivot 10 and right pivot 10′—left segment is to the left of leftpivot 10, intermediate segment is between left and right pivots and theright segment is to the right of right pivot 10′. The left segment mayrotate in relation to the intermediate segment using left pivot 10. Theright segment may rotate in relation to the intermediate segment usingright pivot 10′. The rotations are required during a change directionprocess during which the surface cleaning device changes the directionof movement (and cleaning)—from left to right or from right to left.

When the surface cleaning device has to change its movement from a leftdirection to the right direction the rotation of the left segmentenables the change of movement to succeed. The rotation of the leftsegment is required when the overall length of the surface cleaningdevice exceeds the distance between the upper and lower rails and thusthe distance between the lower segments and the left segment should bechanged when changing the direction. The same applies to the rightsegment.

The motor of the lower wagon 9 pushes the lower wagon to the left 12.Even after an upper part of left stopper 7 contacts a left shaking pipe6 and prevents upper wagon 3 to progress to the left.

The left stopper 7 may act as a pivot—whereas while the motor of lowerwagon 9 continues moving to the left (arrow 16)—the left stopper 7causes the upper wagon 3 and the upper part of the surface cleaningdevice to progress to the right.

When the lower wagon reaches a certain position—for example when thelower end of the axis or rotation 5 reaches the left end of thepanel—the motor of the lower wagon 9 reverses its rotation direction (orany other mechanical arrangement changes the progress direction of thelower wagon)—and the lower wagon—and the entire surface cleaning devicestart moving to the right (see arrow 18 of FIG. 3).

Arrow 15 illustrates the reverse of direction and arrow 17 points to theleft segment of the upper rail—when positioned at an upmost position.

When the turning movement is completed the left segment of the upperrail returns to its lower position.

The same procedure occurs near the right end of the table—when changingthe movement of the surface cleaning device from right to left.

The surface cleaning device when cleaning the surface may generate adust blowing effect.

FIG. 4 illustrates the surface cleaning device 100 as moving in anon-tilted angle (normal to the longitudinal axis of the panel) whenprogressing towards the left end of the panel.

FIGS. 1-3 and 5 illustrate a left shaker pipe 6 and right shaker pipe6′.

When the general cleaning direction is left (and the surface cleaningdevice cleans the surface while moving to the left) then (a) the leftshaker pipe 6 should be “activated” (within the reach or path of thedust carrier members) and the right shaker pipe 6′ should be“deactivated” (outside the reach or path of the right shaker pipe 6′).

When the general cleaning direction is right (and the surface cleaningdevice cleans the surface while moving to the right) then (a) the rightshaker pipe 6 should be “activated” (within the reach or path of thedust carrier members) and the left shaker pipe 6′ should be“deactivated” (outside the reach or path of the left shaker pipe 6′).

This selective activation and deactivation may be facilitated in variousmanners. For example—the right shaker pipe 6′ and the left shaker pipe 6may be moved in and out of reach of the dust carrying members by amanipulator.

There may be a separate manipulator for each one of the right shakerpipe 6′ and the left shaker pipe 6. The manipulation may involve anykind of movement—rotation, turning, linear and the like.

In FIG. 5 the manipulator includes a right frame 21 that is connected tothe right shaker pipe 6′ and a left frame 18 that is connected to theleft shaker pipe 6. These frames are rotated by pivot 20 (rotationdenoted by arrow 24).

The left part of FIG. 5 illustrates a state where the frames are rotatedto the left—the right shaker pipe 6′ is activated and the left shakerpipe 6 is deactivated.

The right part of FIG. 5 illustrates a state where the frames arerotated to the right (arrow 25)—the left shaker pipe 6 is activated andthe right shaker pipe 6′ is deactivated.

The dust carrying member is arranged to direct dust away from the dustcarrying member—and prevent (or at least substantially prevent) the dustthat it removed from returning backwards.

Accordingly—when a segment of the surface was recently cleaned by thedust carrying member—then the dust carrying member will prevent orsubstantially prevent duct from returning to that segment.

The dust carrying member may prevent the dust from moving backwards byperforming at least one out of dust blowing away from the dust carryingmember (especially using air that exits a momentarily compressed gapbetween the wipers), self-cleaning of the dust carrying members (infront of the dust carrying member), and at least partially blocking thebackflow of dust by a wiper that may contact the surface thereby atleast partially blocking the back flow of dust.

FIGS. 6A, 6B, 6C and 6D may illustrate different phases is a cleaningcycle. These figures illustrate first dust carrying member 101 andsecond dust carrying member 102.

In FIG. 6A the first wiper and second wiper (marked in dashed lines) arefully stretched. The first wiper hits the surface of the panel and grabthe dust 28.

When the wiper touches the table surface 29, he cleans the surface andmay grab the dust in his fibers.

In FIG. 6B the wipers continue their rotation and the first wiper movestoward the right shaking pipe 6′.

The first wiper hits the right shaking pipe 6′ thereby removing dust 30from the first wiper. Moreover, since the right shaking pipe 6′ isrounded (compared with the flat surface of the panel 29), the firstwiper loops around the right shaking pipe 6′, and blocked it fromcontinuing the rotation while the following wiper, continues moving.

The first wiper progress is delayed in relation to the progress of thefollowing wiper us appear. This causes a compression (at the generaldirection of cleaning) of the gap between the first wiper and thefollowing wiper. The compression of the gap may be evaluated whencomparing the gap that is illustrated in FIG. 6B to the gap (compressedgap) that is illustrated in FIG. 6C. The compression ratio may exceed 1,2, 3, 4, 5, and the like.

In FIGS. 6B and 6C the following wiper contacts the surface and providea seal (or a substantial seal) that prevents (or substantially prevents)the flow of air behind the following wiper

As in FIG. 6C the following wiper touches the surface and seals the airpath backward and the gap (air pocket) between the wipers iscompressed—resulting in a relatively significant air blow away from thesurface cleaning device.

It should be noted that the first wiper that is wound around the rightshaking pipe 6′ (or otherwise is contacted by the right shaking pipe)also substantially prevents the air from escaping upwards—and may directthe air that escapes the gap not only forwards but also towards thesurface (and the dust that is on the surface).

This air also directs the dust 30 removed from the first wiper (by theright shaking pipe) forwards—away from the surface cleaning device—whilepreventing (or substantially preventing) dust to flow backwards.

In FIG. 6D the rotation of the wipers continues. The first wiper escapesthe right shaking pipe 6′ (it is pushed out from the looped position onthe right shaker pipe 6′) with very small distance between its positionand the wiper behind.

Due to the centrifuge power, along its circulation, the first wiper isstretched out and the gap between the first wiper and the precedingwiper increases wipers again, thereby allowing the gap to expand andform an air pocket for the next blowing routine.

The right shaking pipe is positioned at the direction of the movement ofthe surface cleaning device and increases dramatically the effectivenessof the surface cleaning device as dust that removed from the wiper isblown forwards by a powerful dust blower—without a substantial amount ofdust that moves backward.

The principal of the apparatus detail design has many option based onpreferred wiper material, type of sand in the specific region, length ofthe table, but in all cases the apparatus design may or may not be basedon few principals that may or may not be implemented.

Shaker pipe height from the table—it may be positioned at an angle of upto 125 degrees (zero is down from the pivot toward the panels surface)to create the dust cloud low enough not to spray the dust backward. Thislimitation also allows the wiper another 235 degrees of movement, tillit hits the panel again to be stretched out using the centrifuge force.Nevertheless—the angle of deviation (125 degrees) is a non-limitingexample and the angle may change from 125 degrees.

Wiper length—it may be beneficial to have the wiper loop on the shakingpipes and that the resistance (to backward wind) of the wiper whenmoving along the surface of the panel is much lower than the resistance(amount of force that will free the wiper) of the looped wiper on theshaking pipe. This allows the air pocket between any adjacent wipers toshrink and generate a significant the wind blowing effect.

Positioning of the following wiper to contact the surface during thelooping of the preceding wiper on the shaking pipe. This will provide abackward seal for preventing the air in the gap to flow backwards.

Stretching out process—the end of the wiper may or may not be heavierfor smoothing and hurrying the stretching movement of the wiper alongthe path maximizing the centrifuge force acting on the wipers whilecirculating.

The material of the wiper can changed but the design should attached tothe flexibility and weight of the material.

When implementing at least some of the mentioned above requirements thesurface cleaning device may be benefit from:

-   -   a. An increase in the wind speed in the direction of the panel        (for example—by a factor of four in comparison to rotating        wipers without the shaking pipe).    -   b. Prevent dust from be directed backwards.    -   c. Facilitate a simple and compact system.

In a proof of concept (as described in the picture below—measurements incm described in gray color) the surface cleaning device handled 25 gramper square meter dust (represent heavy dust layer generated on extremesand storm) with wipers that were made of 4200 gsm (gram per squaremeter) microfiber that were folded into two, and the axis of rotationrotated at a speed of 280 round per minute. This surface cleaning deviceachieved in one round of cleaning (cleaning while moving to a singledirection) a reduction of 99% of dust. In this proof of concept thewagon speed was 5 meters per minute.

In this proof of concept the wipers width (distance from the rotatingpipe) were 4.5 cm longer (20 cm) than the distance (15.5 cm) between therotating pipe and the surface of the solar panel.

Due to the high speed of rotation only the last 2 cm of wiper reallytouch the glass—is such case the effective wiping surface of each wiperis 5 cm of glass. If each second the rotating pipe performs 4.5 rounds,then overall 18 wiping operations (4 wipers each round) are executed persecond and the wagon moves 10 centimeters per second.

This proof of concept illustrated a complete clean (over 99% removal ofdust) of 25 gram of dust per square meter of surface (represent amoderate storm), in one round.

Another important device for cost reduction and maintenance reduction isthe ability to move the robot between tables.

FIG. 7 describes using a rail and/or a drone and/or a robotic arm formoving the surface cleaning device from one table to the other.

Any system or device that may carry the surface cleaning device may movethe surface cleaning device. The carrying of the surface cleaning deviceis simplified and is cheaper in comparison to other devices due to thelight weight of the surface cleaning device.

The left side of FIG. 7 illustrates an array of tables 35 that alignedwith adjacent tables 36 and each table and adjacent table are closeenough to enable a rail 37 to be connected to different tables of a rowand thus the drone and/or robotic arm will move the surface cleaningdevice between one row to the other.

The right part of FIG. 7 illustrates tables 39 and 40 that are alignedbut are spaced apart from each other and may require a drone or arobotic arm to move the surface cleaning device between differenttables.

FIG. 8 illustrates a robotic arm 41 that is move the surface cleaningdevice between tables of the same row that are also spaced apart fromeach other and between tables of different rows. A road or wide enoughpath may be formed between the tables and the robotic arm may move alongthe road.

FIG. 9 is a front view of table 101′ surface cleaning device 100 thatillustrates a lower wagon 9, pivot pole 5 that is rotated by motor 1, aframe 117 that supports the pivot pole 5, left shaking pipe 6, rightshaking pipe 6′, pivot 20, engine 13, lower rail 11′ and wheels 118 ofthe lower wagon that are positioned at both sides of the lower rail.

FIG. 10 is a side view of surface cleaning device 100 that illustrates alower wagon 9, pivot pole 5 that is rotated by motor 1, a frame 117 thatsupports the pivot pole 5, left shaking pipe 6, right shaking pipe 6′,pivot 20, engine 13, left frame 18, right frame 21, lower rail 11′ andwheels 118 of the lower wagon that are positioned at both sides of thelower rail.

The pivot pole 5 has holders 161 for holding poles 162 that are attachedto the wipers 163.

FIG. 11 is a top view that illustrates bearing 2 that allows the pivotpole 5 to rotate in relation to the lower rail, motor 1, left and rightshaking pipes 6 and 6′, and lower wagon 9.

FIG. 12 illustrates various wiper interfaces that are not circular.Previous figures illustrated a rotating pole that defined a circularpath—it forced the wipers (at least the inner ends of the wipers) tofollow a circular path. FIG. 12 illustrates wiper interfaces that arenon-circular.

Wiper interface 130 is elliptical, wiper interface 140 approximates arectangle but has round corners and wiper interface 150 is a polygon.The wiper interfaces may be track or any other interfacing element thatmay be moved (directly or indirectly) by one or more motors.

FIG. 13 illustrates surface cleaning device 100 that is powered by solarpanels 61 and 62 that are positioned to the left and the right of thepivot pipe 5. The solar panels may be located in any position—andespecially outside the reach of the wipers. Alternatively, a solar panelmay act as a motion delay element. The solar panels may be positionedabove the pivot pole 5.

FIG. 13 also illustrates pivot pole 5, left and right shaking poles 6and 6′ and two movement mechanism units 71 and 72 for moving the surfacecleaning device 100. The movement mechanism units 71 and 72 t may bewagons or may differ from wagons.

The number of solar panels may be one, two or exceed two.

FIG. 14 illustrates surface cleaning device 100 that has a controller80. The controller 80 may be a hardware controller that may include oneor more integrated circuits. The controller 80 may be positioned in anylocation and may be included in any of the surface cleaning devices 100of any other figure.

The surface cleaning device 100 may include one or more sensors such asbut not limited to (a) at least one environment sensor that isconfigured to sense at least one environmental condition, and/or (b) atleast one state sensor that is configured to sense a state parameter ofthe surface cleaning device.

The at least one environmental sensor may be a humidity sensor. A rainsensor, a temperature sensor, a wind sensor and a sun radiation sensor.

The at least one state sensor may sense the functionality of variouscomponents of the surface cleaning device 100, the energetic state ofthe surface cleaning device 100—especially whether the surface cleaningdevice 100 has enough power to complete a scheduled cleaning task.

The wind sensor may sense the speed of the wind and/or the direction ofthe wind. When the speed of the wind is too high the controller 80 maydecide not to perform any cleaning operation for safety reason.

When the wind sensor detects a wind direction the controller maydetermine not to perform any cleaning operation that attempts to removedust in a direction that is in the general direction of the winddirection.

The controller may determine not to perform any cleaning operation thatattempts to remove dust at a certain direction when (a) the wind speedis a above a certain threshold (significant wind), and (b) the winddirection is in the general direction of the certain direction.

FIGS. 15 and 16 illustrates various sensors 84 and 86. The number ofsensors per surface cleaning device 100 may range between zero and atleast five. Sensors 84 and 86 may represent any type of sensors—statesensors and/or environmental sensors. FIG. 16 illustrates acommunication module 88 of the surface cleaning device in communicationwith another device 400.

FIG. 16 illustrates surface cleaning device 100 without solar panels butwith battery—but the surface cleaning device 100 may include both one ormore solar panels and one or more batteries.

FIG. 17 illustrates that the left and shaking pipes 6 and 6′ may bereciprocated by motors 210, 210′ (or any other manipulators) by one ormore various manners (horizontally, vertically, in a linear andnon-linear manner)—or otherwise cyclically moved so as to contact thewipers while moving.

FIG. 18 illustrates method 300 for dry cleaning.

Method 300 may start by steps 310 and 320.

Step 310 may include moving, using a motor, a first dust carrying memberand a second dust carrying member over the surface. The first and seconddust carrying members are affixed to a motor and step 310 includesmoving the first and second dust carrying members to perform at leastone out of collecting dust and pushing dust primarily in a firstdirection.

Step 320 includes momentarily delaying a motion of a first dust carryingmember approximately at a point where the first dust carrying memberlifts above the surface, and the second dust carrying member is at pointwhere it is configured to at least partially block air passage in asecond direction generally opposite to its current direction of movementrelative to the surface, while air passage is in the direction of thefirst dust carrying member is less impeded.

Steps 310 and 320 may be repeated multiple times—during multiplecleaning cycles.

Method 300 may also include step 330 of moving a surface cleaning devicein relation the surface.

Step 330 may be executed in parallel to steps 310 and 320.

It should be noted that the wagons are merely a non-limiting example ofa movement mechanism units that may move the surface cleaning device.

The surface cleaning device may move on the panel and not on the railsand/or the surface cleaning device may interface with the panel in anyother manner.

The pivot pipe and/or the shaking pipes are merely non-limiting examplesof shaking elements and/or motion delay elements. The shaking elementsand/or motion delay elements may differ from pipes, may be smooth orhave a rugger exterior, may have a cross section that is not circular,and the like.

It should be noted that although the various figures illustrate left andright movements that the surface cleaning device 100 may move along anypattern and in any direction. For example—the surface cleaning device100 may move vertically (up and down), perform a polygon shaped patternand the like. Different patterns may require to hold to the surfacecleaning device 100 to the solar panels in manners that differ fromthose illustrated above.

The surface cleaning device 100 may operate without a frame that ispositioned above the panel—and thus is lower than frame based solutions.This reducing the shading effect of the surface cleaning device 100.

FIG. 19 illustrates the pivot pole as including two segments 5(1) and5(2)—each rotated by a different engine—91 and 92 respectively. Movementmechanism unit 71 includes (or is proximate to) engine 91. Movementmechanism unit 72 includes (or is proximate to) engine 92.

It should be noted that the shaking pipes are not limiting examples of amotion delay element. A motion delay element may have a different shapethan a pipe.

A motion delay element may actively catch the wiper (for example—byusing clips or any gripping elements that perform a movement towards thewiper) and then release the wiper. Non-limiting examples of grabbingelements may be found in almost any robotic arm.

FIG. 20 illustrates that the motion delay elements are robotic—460 and406′ is illustrated in a closed position while robotic arm 406 is in anopen position.

The surface cleaning device may include interfacing elements—such asrings, rails, protuberances, openings that may ease the holding of thesurface cleaning device by a drone and/or a robotic arm and the like.FIG. 21 is a side view of the surface cleaning device 100, a table 101′and tracker or fixed support 102′ that supports the table. FIG. 21illustrates that the upper wagon 3 moves along the upper end of thetable (hence “upper” wagon) while the lower wagon 10 moves along thelower end of the table (hence “lower” wagon). FIG. 22 illustrates method500. Method 500 may include steps 510, 520 and 530. Step 510 may includemoving, using a motor, a first dust carrying member and a second dustcarrying member over a path.

Step 510 may include contacting the surface by the first dust carryingmember while progressing at a first direction; following the contactwith the surface, colliding by the first dust carrier with a shakingmember thereby removing dust from the first dust carrying member;contacting the surface by the second dust carrying member whileprogressing at a first direction; partially blocking by the surfacecleaning device, the dust removed from the first dust carrying memberfrom progressing at a direction that is opposite to the first direction;contacting the surface by the second dust carrying member whileprogressing at the first direction; following the contact with thesurface, colliding by the second dust carrier with the shaking memberthereby removing dust from the second dust carrying member; partiallyblocking by the surface cleaning device, the dust removed from thesecond dust carrying member from progressing at the direction that isopposite to the first direction.

Method 500 may also include step 530 of moving a surface cleaning devicein relation the surface.

Step 530 may be executed in parallel (with a certain overlap or in astaggered manner—even without overlap) to step 510.

Each wiper may stretch along at least a majority of the length of thepivot pipe. Alternatively, multiple wipers may be much shorter than thepivot pipe. Multiple wipers may be arranged in rows, in a staggeredmanner or in any ordered or non-ordered manner to cover at least amajority of the pivot pope (or any other interfacing element thatcontacts the wipers.

In FIG. 23 multiple sets of wipers are arranged in a staggeredmanner—multiple sets (for example—three—or any other number) differentsets of wipers “cover” the length of the pivot pipe—but are positionedat different angles—so that wipers of one set of wipers (connected tothe same segment of the pivot pipe) impacts the surface at differentpoints in time than wipers of another set of wipers (connected toanother segment of the pivot pipe). For example—there may be a timedifference between a time of impact of each wiper of the first set and acorresponding wiper of the second set. In this sense correspondingwipers from different sets may be the wipers with the smallest timingdifferences between their time of impact. Corresponding wipers may be,for example, wipers 603(3), 602(3) and 601(3).

The three sets include four wiper each—601(1)-601(4), 602(1)-602(4) and603(1)-603(4).

In FIG. 23 the different sets of wipers are phase-shifted (oriented) by30 degrees from each other.

FIGS. 23 and 24 illustrate multiple (for example twelve—but any numbermay be provided) sets of wiper holders 610(1)-610(12) that are arrangedin a symmetrical manner about the pivot pipe—at angular displacement of30 degrees from each other.

This allows wipers of different sets of wipers to be arranged in angulardisplacements of products of 30 degrees from each other.

It is noted that the wiper holders may be arranged in an even or unevendistribution.

The staggered arrangement may reduce the forces applied on the surface.

It is noted that any arrangement of the wipers (and of the sets ofwipers) may be provided. The angular displacement between differentwiper holders may be the same- or may differ from each other. The widthsof different wipers may be the same or differ from each other.

One or more wipers of different sets may be aligned with each otherwhile one or more other wipers of the different sets may be misalignedwith each other.

The angular displacement between the wipers of different sets of wipersmay follow any pattern—staggered, non-staggered, ordered, non-ordered,random, pseudo-random- and the like.

The shaker pipe may be replaced by an air condenser that may limit anddirect the air/dust distribution and thus may increase the speed of airthat passes over the surface. In previous figures the space between thesurface and the shaker pipe was entirely open. The condenser reduces theexit aperture to a fraction of the space between the shaker pipe and thesurface.

The condenser may have any shape or size. The cross section of the innerpart of the condenser (that part the faces the dust at the time ofimpingement of the wiper) may be curved, convex, concave, linear,non-linear or may be any combination of linear and/or non-linearsections. In FIG. 26 the inner part is a combination of linear andnon-linear parts.

FIG. 25 illustrates wipers 721, 722, 723 and 724—where wiper 721 impactsthe condenser 700. The wipers are rotated by pivot pipe 5. Condenser 700and surface 790 define an output aperture 781 that is much smaller thanan input aperture 782 defined between the point of impact (with thewiper) and surface 790.

FIG. 26 illustrates a cross section of condenser 700 that includesupporting pipes 701, 702, 703 and 704—as well as outer housing 710 thatincludes sections 711-718, the inner part includes horizontal section712, concave section 713, and sloped section 714.

FIGS. 27 and 28 include a cross sectional view and a perspective view ofan air condenser that differs from the air condenser of FIG. 26 byincluding teeth 719 that interface with the wiper and better shakes thedust from the wiper. There may be any number of teeth. The teeth may bereplaced by any other protuberances/rigid surface and the like.

The wipers may be preceded by dislodging elements that are configured tocontact the surface (before the surface is contacted by the wipers) andattempt to disconnect debris (such as birds dropping or mud) than can belater on can be flown away by the air from the wipers. The dislodgingelements may be wipers, may be rigid or partially elastic. Thedislodging elements may be non-parallel to the pivot pipe—so that theydo not substantially block the air from the wipers. The dislodgingelements may also be shaped and/or sized to direct air toward one ormore desired direction. The combination of the dislodging elements andthe wipers provide a double phase cleaning process that is efficient toclean both debris that may be connected to the surface and also to dustor other elements that are not connected to the surface. This is moreefficient that using only wipers.

In FIGS. 29-31 the wipers are not shown for simplicity of explanation.Dislodging elements 810 are oriented by 45 degrees from the pivot pipe830—although any other angle of deviation can be provided. In FIG. 29-31the dislodging elements are connected to the air condenser 840—but anymechanical coupling of the dislodging elements to the system may beprovided. The dislodging elements of FIGS. 29-31 have a rectangularshape—but may have other shapes. They may form apertured shapes—but thisis not necessarily so. FIG. 29 illustrates a surface cleaning device 800that includes the dislodging elements.

The system may move in two directions—but the dislodging elements may bepositioned on only one side of the system—or on both sides of thesystem. The shape, size and number of dislodging elements may differfrom those illustrated in FIGS. 29-31.

In the foregoing specification, the invention has been described withreference to specific examples of embodiments of the invention. It will,however, be evident that various modifications and changes may be madetherein without departing from the broader spirit and scope of theinvention as set forth in the appended claims.

Moreover, the terms “front,” “back,” “top,” “bottom,” “over,” “under”and the like in the description and in the claims, if any, are used fordescriptive purposes and not necessarily for describing permanentrelative positions. It is understood that the terms so used areinterchangeable under appropriate circumstances such that theembodiments of the invention described herein are, for example, capableof operation in other orientations than those illustrated or otherwisedescribed herein.

Those skilled in the art will recognize that the boundaries betweenblocks are merely illustrative and that alternative embodiments maymerge blocks or circuit elements or impose an alternate decomposition offunctionality upon various logic blocks or circuit elements. Thus, it isto be understood that the architectures depicted herein are merelyexemplary, and that in fact many other architectures may be implementedwhich achieve the same functionality.

Any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality may be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected,” or“operably coupled,” to each other to achieve the desired functionality.

Furthermore, those skilled in the art will recognize that boundariesbetween the above described operations merely illustrative. The multipleoperations may be combined into a single operation, a single operationmay be distributed in additional operations and operations may beexecuted at least partially overlapping in time. Moreover, alternativeembodiments may include multiple instances of a particular operation,and the order of operations may be altered in various other embodiments.

However, other modifications, variations and alternatives are alsopossible. The specifications and drawings are, accordingly, to beregarded in an illustrative rather than in a restrictive sense.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. The word ‘comprising’ does notexclude the presence of other elements or steps then those listed in aclaim. Furthermore, the terms “a” or “an,” as used herein, are definedas one or more than one. Also, the use of introductory phrases such as“at least one” and “one or more” in the claims should not be construedto imply that the introduction of another claim element by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim element to inventions containing only one suchelement, even when the same claim includes the introductory phrases “oneor more” or “at least one” and indefinite articles such as “a” or “an.”The same holds true for the use of definite articles. Unless statedotherwise, terms such as “first” and “second” are used to arbitrarilydistinguish between the elements such terms describe. Thus, these termsare not necessarily intended to indicate temporal or otherprioritization of such elements. The mere fact that certain measures arerecited in mutually different claims does not indicate that acombination of these measures cannot be used to advantage.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents will now occur to those of ordinary skill in the art. It is,therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the true spiritof the invention.

What is claimed is:
 1. A surface cleaning device for cleaning a surfaceof a solar panel, wherein the surface cleaning device comprises: a firstdust carrying member; a second dust carrying member; a motor; and amotion delay assembly; wherein the first dust carrying member and thesecond dust carrying member are coupled to the motor; wherein the motoris configured to cyclically move the first dust carrying member and thesecond dust carrying member along a path; wherein the motion delayassembly is configured to cyclically introduce a momentarily delay in aprogress of the first dust carrying member along the path, while thesecond dust carrying member contacts the surface thereby reducing a gapbetween the first dust carrying member and the second dust carryingmember and induce air to exit the gap and progress along the surface andremove dust that precedes the second dust carrying member whereinsurface cleaning device is configured to position the motion delayassembly at a first position when the surface cleaning device propagatestowards one end of the surface and is configured to position the motiondelay assembly at a second position when the surface cleaning devicepropagates towards another end of the surface; wherein when positionedin the first position the motion delay assembly is within a reach of thefirst dust carrying member; and wherein when positioned at the secondposition the motion delay assembly is outside the reach of the firstdust carrying member.
 2. The surface cleaning device according to claim1 wherein the second dust carrying member, when contacting the surface,is configured to at least partially prevent an exit of the air from thegap towards dust that resides on the surface and follows the second dustcarrying member.
 3. The surface cleaning device according to claim 1wherein the motion delay assembly is configured to induce the air toexit the gap at a first direction; wherein the second dust carryingmember contacts the surface while progressing along the first direction.4. The surface cleaning device according to claim 1 wherein during asingle cycle the first dust carrying member is configured to contact thesurface at a first point in time and wherein the motion delay assemblyis configured to introduce the momentarily delay at a second point oftime that follows the first point of time.
 5. The surface cleaningdevice according to claim 1 wherein the momentary delay is of a firstduration; wherein the first duration exceeds a duration of a delayimposed on a progress of the second dust carrying member due to acontact between the surface and the second dust carrying member.
 6. Thesurface cleaning device according to claim 1 wherein the motion delayassembly is configured to cyclically introduce the momentarily delay inthe progress of the first dust carrying member without substantiallydelaying a progress of the second dust carrying member along the path.7. The surface cleaning device according to claim 1 wherein the motiondelay assembly is further configured to remove dust from the first dustcarrying member while introducing the momentarily delay.
 8. The surfacecleaning device according to claim 1 wherein the motion delay assemblyis configured to cyclically introduce a momentarily delay in a progressof the second dust carrying member along the path, while the first dustcarrying member contacts the surface, thereby reducing the gap betweenthe first dust carrying member and the second dust carrying member andinducing air to exit the gap and progress along the surface and removedust that precedes the first dust carrying member.
 9. The surfacecleaning device according to claim 1 wherein the motor is configured tocyclically move the first dust carrying member and the second dustcarrying member along the path by rotating the first dust carryingmember and the second dust carrying member about an axis of rotation.10. The surface cleaning device according to claim 1 wherein the motiondelay assembly comprises: a first motion delay element that ispositioned at a first side of the motion delay assembly; a second motiondelay element that is positioned at a second side of the motion delayassembly; and a manipulator that is configured to selectively positionat least one of the first and second motion delay elements within thepath of the first dust carrying member.
 11. The surface cleaning deviceaccording to claim 1 wherein the motion delay assembly comprises a firstmotion delay element that is positioned at a first side of the motiondelay assembly, a second motion delay element that is positioned at asecond side of the motion delay assembly and a manipulator that isconfigured to position the first motion delay element within the path ofthe first dust carrying member when the surface cleaning devicepropagates towards an end of the surface and to position the secondmotion delay element within the path of the first dust carrying memberwhen the surface cleaning device propagates towards another end of thesurface.
 12. The surface cleaning device according to claim 1 comprisinga group of dust carrying members, wherein the dust carrying memberscomprises the first and second dust carrying members and at least oneadditional dust carrying member.
 13. The surface cleaning deviceaccording to claim 1 comprising at least one environment sensor that isconfigured to sense at least one environmental condition.
 14. Thesurface cleaning device according to claim 13 comprising a controllerthat is configured to control the operation of the surface cleaningdevice based on one or more environmental conditions of the at least oneenvironmental condition.
 15. The surface cleaning device according toclaim 1 comprising at least one battery for providing electrical energyfor powering the surface cleaning device.
 16. The surface cleaningdevice according to claim 1 consisting essentially of the motor, themotion delay assembly and a group of dust carrying members, wherein thegroup of the dust carrying members comprises the first and second dustcarrying members.
 17. The surface cleaning device according to claim 1,further comprising at least one dislodging element that precedes thefirst dust carrying member and the second dust carrying member, and isconfigured to contact the surface and disconnect debris from thesurface; and wherein the surface cleaning device is further configuredto induce the air to exit the gap and progress along the surface andalso remove the debris.
 18. The surface cleaning device according toclaim 17, wherein the at least one dislodging element is neitherparallel and neither perpendicular to an axis of rotation of the motor.19. The surface cleaning device according to claim 17, wherein the atleast one dislodging element comprises multiple plates.
 20. The surfacecleaning device according to claim 17, wherein the at least onedislodging element is made of a rigid material.
 21. The surface cleaningdevice according to claim 17 wherein the at least one dislodging elementcomprises multiple plates that are shaped and positioned to divert aprogress of the air.
 22. The surface cleaning device according to claim21 wherein the air condenser is configured to increase a speed of airexited from the air condenser.
 23. The surface cleaning device accordingto claim 21 wherein a distance between the surface and a lower end ofthe air condenser is a fraction of a height difference between thesurface and a point of contact between the second dust carrying member.24. The surface cleaning device according to claim 21 wherein the aircondenser comprises teeth that are positioned at an area of the aircondenser that is in contact with the dust carrier members.
 25. Thesurface cleaning device according to claim 1 wherein the motion delayassembly comprises an air condenser.
 26. The surface cleaning deviceaccording to claim 1 comprising multiple spaced apart sets of dustcarrier members, wherein the sets of dust carrier members comprise thefirst and second dust carrier members.
 27. The surface cleaning deviceaccording to claim 1 comprising multiple staggered sets of dust carriermembers, wherein the sets of dust carrier members comprise the first andsecond dust carrier members.
 28. The surface cleaning device accordingto claim 1 wherein each dust carrier member is flexible.
 29. A surfacecleaning device for cleaning a surface of a solar panel, wherein thesurface cleaning that comprises: a first dust carrying member; a seconddust carrying member; a motor; and a shaking member; wherein the firstdust carrying member and the second dust carrying member are coupled tothe motor; wherein the motor is configured to cyclically move the firstdust carrying member and the second dust carrying member along a path;wherein the first dust carrying member is configured to (a) contact thesurface while progressing at a first direction, and following thecontact with the surface (b), collide with the shaking member therebyremoving dust from the first dust carrying member; and wherein thesurface cleaning device is configured to at least partially block thedust removed from the first dust carrying member to progress at adirection that is opposite to the first direction.
 30. The surfacecleaning device according to claim 29 wherein the a first dust carryingmember and the second dust carrying member are wipers.
 31. The surfacecleaning device according to claim 29 wherein the a first dust carryingmember and the second dust carrying member are wipers that comprisesmicrofiber fibers.
 32. The surface cleaning device according to claim 29comprising an additional shaking element, wherein the first dustcarrying member is configured to (a) contact the surface whileprogressing at a second direction that differs from from the firstdirection, and following the contact with the surface (b), collide withthe additional shaking member thereby removing dust from the first dustcarrying member; and wherein the surface cleaning device is configuredto at least partially block the dust removed from the first dustcarrying member to progress at a direction that is opposite to thesecond direction.
 33. A method of cleaning a surface, comprising:moving, using a motor, a first dust carrying member and a second dustcarrying member over the surface, where the first and second dustcarrying members are mechanically coupled to a motor such that when themotor is activated the motion of the first and second dust carryingmembers are configured to perform at least one out of collecting dustand pushing dust primarily in a first direction; momentarily delaying,by a motion delay assembly, a motion of the first dust carrying memberapproximately at a point where the first dust carrying member liftsabove the surface, and the second dust carrying member is at point whereit is configured to at least partially block air passage in a seconddirection generally opposite to its current direction of movementrelative to the surface, while air passage is in the direction of thefirst dust carrying member is less impeded; positioning the motion delayassembly at a first position when the surface cleaning device propagatestowards one end of the surface; positioning the motion delay assembly ata second position when the surface cleaning device propagates towardsanother end of the surface; wherein when positioned in the firstposition the motion delay assembly is within a reach of the first dustcarrying member; and wherein when positioned at the second position themotion delay assembly is outside the reach of the first dust carryingmember.